Visibility control by means of polarization effects



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VISIBILITY CONTROL BY MEANS OF POLARIZATION EFFECTS Filed July 6, 1940 g. Ul'llL-O Patented June 16, 194-2 uuulbil laLrUl' VISIBILITY CONTROL BY MEANS OF POLARIZATION EFFECTS Leon Pollack, Brooklyn, N. Y.

Application July 6, 1940, Serial No. 344,229

13 Claims.

This invention relates broadly to an arrangement for controlling the visibility of a room or a group of rooms, and is a continuation-in-part of my application Serial No. 193,543, filed March 2, 1938.

The term room is used in this specification and in the appended claims to designate any space for human occupancy enclosed on all sides, such as a room in a building, the interior of an automobile or a railroad car. These illustrations, however, are not to be regarded as restrictive or limitative of the uses of the invention.

One of the objects of the present invention is to so illuminate a room that an occupant is enabled to see outside through a window, while a person outside cannot view the room by means of the illumination in the room.

Another object is to so design a group of adjoining or alternately arranged rooms that an occupant of one room can look into an adjoining room but cannot look through said adjoining room into the next room.

By means of the present invention the following results can be achieved. First, so to illuminate a room of a house that it is impossible for a person on the outside (such as a passerby) to view the interior of the room at night by virtue of the illumination in the room, while permitting the occupant of the room to view the room clearly (in order to read, dress or undress) and to look out through the window to observe what is going on outside of the house, thus assuring strict privacy. Second, so to arrange the side windows of a room that an outsider can look into the room through one window but cannot look through the room through another side window into an adjoining space, while permitting an occupant of the room to look out through either side window. This last aspect of the invention is especially useful where there are alternately arranged executive and secretarial rooms, thus enabling an executive located in an oflice to look through a window into an adjoining secretarial room but preventing this executive from looking through the secretarial room into the next executive office. And third, so to combine the foregoing first and second results that at no time is the illuminatin'g source of light within the room visible to a person outside the room, and at no time is the ability of the occupant of the room to look out through the windows interfered with.

In accordance with one embodiment of the present invention it is proposed to plane polarize the rays of light emitted by. a light source illuminating a room, and to prevent these rays from being seen outside the room by providing each window with a polarizing screen positioned so as to block or substantially block the polarized light emanating from the source. As an illustration, where the illuminating source emits light polarized in a. horizontal plane, the window will transmit only light which is polarized in a vertical plane, and vice versa. In order to prevent diifusion or depolarization of the light after it has been polarized, the side walls, the ceiling and the floor of the room are made to be of a non-lightreflecting character. A dark or black wall, or

the use of suitably colored drapes and rugs can accomplish the desired result.

In accordance with another embodiment of the invention it is proposed to provide a group of alternately arranged rooms with adjoining rooms having a common side wall. The side walls of each room which are common with the adjoining rooms are provided with light polarizing windows whose polarizing axes are arranged at right angles to each other.

Other objects and features of the invention will be apparent from a reading of the following description which is given in conjunction with drawing, wherein:

Figs. 1 and 2 illustrate the principles of the invention applied to a single room; and

Fig. 3 illustrates the principles of the invention applied to a group of adjoining rooms.

Referring to Fig. 1 in more detail there is shown, in perspective, a room having side walls I, 2, 3, a ceiling 4 and a floor 5. The room is seen as viewed from the fourth side wall. A source of light 6 is set into the ceiling 4 for illuminating the room, and a transparent polarizing body or screen 1 is positioned between the illuminating source 6 and the interior of the room for plane polarizing the rays of light emitted by the source and entering the room. Screen I is preferably arranged to be flush with the surface of the ceiling, and may comprise any suitable plane polarizing body. Such a body may, for example, comprise a transparent suspending medium having a mass of transparent colloidal polarizing particles dispensed therein with their polarizing axes oriented substantially parallel, or

an optically transparent and solidified plastic; such as glass, in which there are embedded a plurality of parallelly arranged electrically conducting paths. These paths may consist of extr'emely t wgwsuch a platinuin or silver, arranged 0 or more to the inch.

All of the side walls and the floor and ceiling of the room are made to be of a non-light-refiecting character. For this purpose, they are either painted black or draped with dark non-light-reflecting fabrics. If the room is the interior of an automobile, it will be appreciated that the fabric used to cover the walls and the roof of the car should possess this desired characteristic.

The windows 8, 9 and HI for the room are provided with polarizing bodies of the same type as I and arranged relative to the angle of polarization of the rays of plane polarized light entering the room from screen 1 so that they are optically crossed (i. e., at right angles) to such rays, whereby little or no light in the room can be seen by a person outside the room looking through the windows. In other words, the windows, which transmit only plane polarized light, are so positioned with respect to the polarizing screen 1 associated with the light source 6 as to block or substantially block the polarized light emitted therefrom. The broken lines indicate the plane of polarization of the light passing through the polarizing bodies.

It will be noted from an inspection of Fig. 1 that polarizing window 9 transmits plane polarized light whose rays are perpendicular to the rays of light which polarizing windows 8 and ID are adapted to transmit. This arrangement of the windows is necessary because of the particular positioning and location of the polarizing screen I, but all of the windows are properly positioned to block the polarized light rays from source 6.

Although the arrangement of the polarizing screen 1 and the polarizing windows are such as to block or materially reduce the light observable by a person outside the room looking through the windows, it will be evident that an occupant of the room can readily see outside through these same windows; also, if there is any unpolarized light in the room a person outside the room looking through a window will have no difficulty viewing the interior. It will be obvious, of course, that because of the positioning of the polarizing axes of windows 9 and H], a person outside viewing the interior of the room through window 9 or It] will not be able to see through both of these windows.

Fig. 2 shows another way of plane polarizing the light from a source of illumination. In this figure the source of light is a lamp placed on a table II and the polarizing system is the lamp shade l2, all of whose plane surfaces are plane polarizing bodies. The polarizing window I3 is adapted to transmit only polarized light, preferably plane polarized, and is so positioned with respect to the surfaces of lamp shade |2 as to block the polarized light emitted therefrom.

Fig. 3 shows a group of alternately arranged and adjoining executive and secretarial rooms |4, |5, l6, l1 and I8. These rooms are provided with light polarizing windows I9, 20, 2| and 22, as shown. Here again, the broken lines indicate the planes of polarization of the light passing through the windows. It should be noted that the planes of polarization of windows I9 and 2| are at an angle of 45 to the horizontal and are parallel, and that the planes of polarization of Windows and 22 are also at an angle of 45 to the horizontal, but positioned at 90 or right angles to the planes of windows |9 and 2|. With such an arrangement the polarizing window 20 completely blocks any light passing through windows l9 and 2|, and the polarizing window 2| completely blocks any light passing through windows 20 and 22. It will thus be 'apparent that the occupant of rooms l5 and I! cannot see each other through room l6, -that the occupants of rooms I6 and I8 cannot see each other through room I1, and that the occupants of rooms l4 and It cannot see eachother through room l5. If it is assumed that rooms l4, I6 and I8 are executive rooms, and rooms l5 and I! secretarial rooms, or vice versa, it will be obvious that an executive in one room can look into the adjoining secretarial room (when the secretarial room is illuminated in ordinary fashion, such as by daylight or ordinary light) but cannot look through the adjoining secretarial room into the next executive room. Either the third or fourth side wall of each of these rooms, not shown, is preferably provided with a window facing the street so as to obtain daylight illumination. Ordinary artificial illumination for these rooms may be obtained from a light in the ceiling, or, if desired, the rooms can be artificially illuminated by polarized light in the manner described in connection with Figs. 1 and 2 so that an occupant of one room cannot see the interior of an adjoining room when the latter is illuminated solely by this polarized light.

It is to be distinctly understood that the term window" used in the specification and in the appended claims is intended to include any optically transparent element serving as an entire wall or a part thereof for enabling a person to view the interior of the enclosed space from a point outside said space.

It should also be understood that the invention is not limited by the arrangements shown in the drawing, since various modifications may be made without departing from the spirit and scope thereof. For example, the planes of polarization of the windows of Fig. 3 can obviously take different angles than those shown in the drawing (for example, horizontal and vertical positions) so long as the polarizing windows on opposed walls of the same room are optically crossed. Also, the principles of the invention are applicable to rooms separated by a skylight shaft or courtyard, wherein the side walls of the rooms which face each other on opposite sides of the yard are provided with polarizing screens in optically crossed relation, said rooms having other windows, also, for permitting daylight to enter therein.

What is claimed is:

1. A lighting system for an enclosed space having side, top and bottom walls of a nonlight-reflecting character, comprising a source of light for said space having means for plane polarizing the rays emanating from said source, and a pair of vertically arranged windows located on dilferent side walls of said room and being so constructed and arranged as to transmit only light polarized in planes substantially at right angles to the plane of said rays, said windows being substantially optically crossed relative to each other.

2. A lighting system for a room comprising a source of light in said room having means for polarizing in a predetermined plane the rays emanating from said source, said room having a pair of side walls each having a transparent window, each of said windows comprising a polarizing body arranged to block light polarized in said plane, the polarizing axes of said pair of windows being substantially at right angles to each other.

3. A lighting system for a room having substantially non-reflecting walls and a substantially non-reflecting ceiling, comprising a source of light for said room set into said ceiling, a polarizing screen positioned substantially in the plane of said ceiling for polarizing in a predetermined plane the rays emanating from said source, and a window set into a side wall of said room and arranged to transmit only light polarized in a plane perpendicular to said predetermined plane, whereby the light from said source available to an observer outside said room looking through said window is materially reduced.

4. A lighting system for a room comprising a source of light in said room having means for polarizing in a predetermined plane the rays emanating from said source, said room having a pair of side walls each having a transparent window, each of said windows comprising a polarizing body arranged to block light polarized in said plane.

5. A lighting system for a room comprising a source of light in the ceiling of said room having means for polarizing in a predetermined plane the rays emanating from said source, and a window set into a side wall of said room and arranged to transmit only light polarized in a plane perpendicular to said predetermined plane, whereby the light from said source available to an observer outside said room looking through said window is materially reduced.

6. A group of rooms comprising, first, second and third adjoining rooms in the order named, said first and second rooms having a common wall, and said second and third rooms also having a common wall, a, window arranged to pclarize light located in each of said common walls, the window in one of said common walls being arranged to block the light passing through the window in the other common wall, whereby an occupant in said second room can view the interior of said first and third rooms through their respective windows in the common side walls but the occupants of said first and third rooms cannot see each other through said second room by looking through both of said windows.

7. A group of rooms comprising first, second and third adjoining rooms in the order named, said first and second rooms having a common side wall, and said second and third rooms having a common side wall, a vertical window comprising a light polarizing body arranged to plane polarize light located in each of said side walls, the polarizing axes of said pair of windows being substantially at right angles to each other.

8. A group of alternately arranged executive and secretarial ofiices, said ofl'lces adjoining one another and being arranged so that adjacent omces have a common side wall, a window located in each side wall which is common to a pair of adjacent offlces, said windows being composed of light polarizing screens, the polarizing axes of alternate ones of said windows being parallel while the polarizing axes of ad- Search Less;

jacent ones of said windows are at relative to each other, whereby an occupant of an executive ofiice can view the adjoining secretarial office through the polarizing window in the common sidewall but cannot see through the adjoining secretarial ofiice into the next executive oifice.

9. A group of rooms in accordance with claim 8, characterized in this that said windows are on opposite sides of the rooms.

10. A group of rooms comprising first, second and third adjoining rooms in the order named, said first and second rooms having a common wall, and said second and third rooms also having a common wall, means providing daylight illumination for each of said rooms, a window arranged to polarize light located in each of said common walls, the window in one of said common walls being arranged to block the light passing through the window in the other common wall, whereby an occupant in said second room can view the interior of said first and third rooms through their respective windows in the common side walls but the occupants of said first and third rooms cannot see each other through said second room by looking through both of said windows.

11. In a building, a pair of rooms having an unobstructed space between confronting side walls of said rooms, a window in each of said confronting side walls, each window being arranged to polarize light transmitted therethrough, said windows being substantially optically crossed relative to each other, whereby a person can view the space between said rooms through either window but cannot see through both of said windows, and means in each room of said pair for enabling daylight illumination to enter.

12. In a building, a pair of rooms having an unobstructed space between confronting side walls of said rooms, a window in each of said confronting side walls, each window being arranged to polarize light transmitted therethrough, said windows being substantially optically crossed relative to each other, whereby a person can view the space between said rooms through either window but cannot see through both of said windows, and means in each room supported by a surface of the room for illuminating the room with light polarized in a plane at right angles to the plane of polarization of one of the windows in said room.

13. In a building, a pair of side walls having an unobstructed space therebetween. a window for each of said walls, each window being arranged to polarize light, said windows being substantially optically crossed relative to each other, whereby a person can view the space between said windows through either window but cannot see through both of said windows, and means for illuminating the space between said walls with light polarized in a plane substantially at right angles to the plane of polarization of at least one of said windows.

LEON POLLACK. 

